Method of molding concrete and mold structure



l. H. MASON 3,157,098

METHOD OF MOLDING CONCRETE AND MOLD STRUCTURE Nov. 17, 1964 Filed Aug. 29, 1961 United States Patent Irvin H. Mason, 2111 Scott Drive, Fairfax, Va. Filed Aug. 29, 1961, Ser. No. 134,743 1 Claim. (Cl. 94-31) This invention relates to a method for molding concrete within molds incorporating precast concrete sheets, and more particularly, to a method of making curbings, sidewalks, and the like, and the mold structure therefor.

In the present state of the art, concrete is generally formed in molds or forms of wood, metal, or fibrous material, or combinations thereof. These are constructed to have the inner surface define the outer surface of the concrete product. Concrete is poured into the forms or molds in a plastic state. Subsequently, when the concrete has attained a solid state, the forms or molds are removed from about the concrete product. They are then disassembled and destroyed, or cleaned and reused for further concrete molding. The removal of forms or molds is known in the art as stripping and is often laborious and costly and, in certain applications, hazardous. The operation of removing the forms, the initial and maintenance costs of the forms and other storage and handling expense, add substantially to the ultimate cost of the concrete product.

A further inconvenience and expense which occurs with certain types of forms or molds such as curb and gutter molds arises through the circumstance that it is usually necessary to remove or loosen them, at least in part, within a matter of hours after the concrete has been placed. This is necessary in order to smooth out the exposed surfaces by hand and to edge the concrete as required.

For certain specific types of structures, it has been suggested that the foregoing difiiculties can be obviated by the use of concrete slabs in place of the wooden or metal forms. An example of such prior art may be found in Patent No. 1,053,646 of Charles Wesley Roberts which was issued February 18, 1913. However, this, and the other prior art, contemplated the use of heavy concrete slabs which are difficult to transport and to handle. The quality of the slabs was usually the same as the filler with the consequence that the structure produced was less strong than comparable structures produced by conventional methods. Moreover, securing problems were often involved and as a result of such drawbacks, prior art devices and processes of this nature have not been widely accepted.

It is an object of the present invention to provide an arrangement whereby improved concrete molds can be employed as a means of improving the quality and appearance of concrete structures and products. It is a further object to provide a method to produce concrete products such as curbing, sidewalks, and highways by the utilization of concrete molds which is more economical than existing methods wherein wooden or metal molds are employed. It is a still further object of this invention to provide a method for producing concrete products more efliciently than the presently utilized methods by the elimination of the labor and expense necessary for the finishing and curing operations. It is a yet further object of this invention to provide an improved concrete product which is superior in appearance and strength to existing similar products.

Other and more detailed objects and advantages of my invention will be evident from the following description and accompanying drawings wherein, by way of example, one method of carrying out the invention is illustrated. It will, of course, be appreciated that the draw- 3,.l57fi98 Patented Nov. 17, 1964 ings and the description are illustrative only, and are not intended to limit the invention except insofar as it is limited by the claim.

In the drawings:

FIGURE 1 is a perspective view showing a mold produced in accordance with my invention for the construction of a curbing;

FIGURE 2 is a sectional view of the mold shown in FIGURE 1 but with the concrete already poured;

FIGURE 3 illustrates the securing means of the concrete sheets to the dividers;

FIGURE 4 illustrates a support securing ring;

FIGURE 5 is an enlarged section of a concrete sheet in accordance with the invention; and

FIGURE 6 is a sectional view similar to FIGURE 2 of a finished curbing from a modified mold structure.

As shown in the drawings there is an after or rear concrete sheet 10 which extends from its lower edge normally from the ground 11the ground 11 having previously been prepared to accommodate forms for a curbing. The concrete sheet 10 is composed of cementitious material which preferably includes as a component, a fibrous material such as asbestos or silica fiber which adds to the tensile strength of the concrete. Reinforcement such as wire mesh is generally embedded within the sheet. For certain applications, prestressed reinforcement is employed. The outside or facing 12 of the sheet 1d is generally smooth, whereas the inner portion 14 is roughened by protruding aggregate or other means or indented in a waffle-like manner to permit increased engagement with the poured concrete 13 to ensure thereby that sheet 10 is effectively bonded to the poured concrete 13. Sheet 10 is normally less than threequarters inch or two centimeters in thickness and can be transported, and handled or even sawed with relative ease.

A further concrete sheet 15 is provided forwardly of the sheet 10 and is spaced parallel therewith. It will be noted that sheet 15 is similar to sheet 10 except that it does not extend as high from the ground 11. The sheets 10 and 15 are secured together in a rectangular form by division plates 16 and 17. These division plates are L- shaped but are otherwise of the same structure as the sheets 10 and 15. They serve the dual purpose of forms and construction joints which control cracking due to contraction. However, every third or fourth division plate is made of fiber board impregnated with asphalt to provide an expansion joint for the curbing. It will be noted that division plates 16 and 17 have along their vertical edges a plurality of apertures 19. These apertures 19 correspond to further apertures 20 (see FIG- URE 3) which are in the vertical edges of the sheets 19 and 15. Dowels or pins 21 are received in the apertures 19 and 20 to secure the division plates 16 and 17 to the sheets 10 and 15. A further facing sheet 22 is held above the surface of the ground by the division plates 16 and 17 in the same manner as sheets 10 and 15 are secured theretothat is, by means of pins 21 in apertures 19 and 2% Sheet 22 is constructed in the same manner as sheets Ill and 15 with a smooth outer surface and an indented inner surface for an efiicient bond with the poured concrete. In order to secure sheet 22 in an additional manner, face forms bracing brackets 24 and 25 hold the sheet 22 relative to the sheet in when the concrete is poured.

Sheets 10 and 15 are secured relative to the ground by means of stakes 26 and 27. These stakes are driven in the ground proximate to the corresponding sheet 10 or 15. A plurality of longitudinal slots 29 is provided through sheets 10 and 15. A support securing ring 30 is placed through slot 29 and twisted so that its end portions 31 are secured on the inner side of the sheet or 1:3 and the loop portion 32 is secured on the outside portion of the sheet concerned. The neck portion 34 remains in the slot 30. Stakes 26 and 2'? are then driven into the ground 11 through the loop portion 32 of each securing ring 30. When this is accomplished, intermediate means comprising rods 35 are inserted horizontally between the stakes 26 and 27 and the sheets 10 and 15 above each of rings 30. it will be appreciated that these rods 35 embrace sheets 10 and 15 longitudinally and increase the ri idity of the mold. Rods 33 are interrupted by brackets 24 and 25 and are therefore shorter than the corresponding rods 35.

Rings are made of spring steel. When in position as shown in FIGURE 2 with rods inserted between stakes 26 and 27 and sheets 10 and 15, the end portions 31 of the rings 30 are compressed to provide that the sheets 10 and 1.5 are securely fastened in place. it will be noted that within limits the positions of the sheets 10 and 15 are adjustable and if necessary small inserts or shims 36, such as shown in FIGURE 2, between stake 26 and rod 35 may be inserted to improve the alignment of the sheet involved.

When the molds are in place, concrete 13 is applied therein and compacted in the usual manner. The surface is thereafter screeded, struck, and otherwise finished as necessary. After the concrete is solid, brackets 24 and 2S and stakes 26 and 27 are removed. Rings 30 are normally clipped off and the slots 29 may, if desired, be filled with cementitious material. It will be appreciated that for certain purposes, it is more desirable that the stakes 26 and 27 be placed within the mold to become a part of the finished product. In such instances, the stakes are preferably made of prestressed concrete. In curbing, this is particularly desirable because the subsequent construction of the roadway frequently tends to 'misarrange the curbing-a circumstance which the stakes in situ help to prevent. FEGURE 6 is an illustration of such a finished curbing, designated 13A. The stakes are designated 26A and 27A and the support securing rings as 30A.

From the foregoing it will be appreciated that sheets such as sheets 10, 15 and 22 may be produced to retain the plastic concrete independently or in conjunction with other devices for internal or external bracing. Precast sheets such as 10, 15 and 22 become the external surface of the structure they define. In other words, they become an integral part of the structure. While in the above-described embodiment we show the concrete 13 bonded to the sheets 10, 15 and 22 by mechanical means, that is to say, by virtue of the roughened interior surfaces 14 of the sheets, it will be understood that they may also be bonded by protruding reinforcements or chemically by well-known commercial bonding agents. The forms are produced in any desired size or shape as suitable for the requirements of the structure or the product to be formed and they can be given any known finish in various colors, shades and textures as desired. Further, when desired, decorative patterns of various types are easily set in the exposed face. Since the forms are produced in greater strength than that of the structure or product which they include, the overall strength of the concrete structure is significantly increased.

It will be appreciated that the commercial success of the product described herein depends in large extent upon the obtention of relatively thin sheets such as 4- sheets 1'10, 15 and 22, with a high fiexural strength such that they do not break easily and are amenable to reasonably rough handling. A practicable method found to increase the flexural strength of these sheets is by the application of strong moisture resistant paper or sealing tape (with adhesive) to one or both sides of the sheet. Such application increases the fiexural strength of the sheet by and more. The application of such paper backing is shown in FIGURE 5, wherein a paper tape 40 with adhesive 4-1 is applied to sheet 10 on face 12 and a further paper tape 42 with adhesive 43 is applied to the indented face 14 of sheet 10. Paper tape 42 is, of course, removed'before concrete 13 is poured and paper tape 40 is removed after the curbing or similar structure has been formed.

The basic process involved herein may be extended to various types of structures and precast products which include, but are not limited to: walls, retaining walls and dams, bridge piers, abutments and decks, beams, girders, columns, floor and roof slab bottoms and edges, highway and airport pavement edges, sidewalk edges, stair soffets, risers and edges, precast structural members and products, footing edges, culverts, tunnels and conduits, curbs, curb and gutter combination, and a variety of construction joints as will occur in the foregoing.

Since changes, variations and modifications in the form, construction and arrangement of the various steps and elements described may be had without departing from the spirit of the invention, it is to be understood that invention in this case is limited solely by the scope of the appended claim rather than by any details of the illustrative showing in the foregoing description.

I claim:

In a concrete structure which includes at least two surfaces extending normally from the ground, a concrete lamina facing along said surfaces comprising concrete sheets which are less than two inches in thickness and which contain reinforcement means, and concrete stakes embedded in said structure extending into the ground therefrom, said stakes interconnected to said sheets.

References Cited by the Examiner UNITED STATES PATENTS 289,295 11/83 McLean 94-24 877,870 1/08 Shone et al 25-118 1,110,295 9/14 Phillips 948 1,471,074 10/23 Trester 94-31 1,684,624 9/28 Hayden 25-122 X 1,789,829 1/31 Moore 94-31 2,191,461 2/40 Ford 50-313 2,332,166 10/43 Reiner 25-131 2,586,912 2/52 Braum 25-118 2,626,444 1/53 Wolf et al. 25-118 2,668,342 2/54 Nelsson 50-313 2,688,174 9/54 Hogan 25-118 2,894,307 7/59 Hogan et al 25-118 2,894,310 7/59 Hogan et a] 25-118 2,989,794 6/61 Bittner 25-131 3,037,433 6/62 Maher 94-31 FOREIGN PATENTS 480,927 3/38 Great Britain. 907,704 7/ 45 France.

JACOB L. NACKENOFF, Primary Examiner.

WILLTAM J. STEPHENSGN, Examiner. 

